On Tue, Mar 21, 2023 at 10:54:32AM +0800, zhuyinbo wrote:
> 在 2023/3/20 下午8:52, Mark Brown 写道:

> > No, that doesn't help if setup() reconfigures the controller while it's
> > doing a transfer.  The issue is that the controller might be put into
> > the wrong mode or run at the wrong speed.

> sorry, I don't got that why cpu still can call setup's critical region when
> cpu call transfer_one to  transfer spi data.

> when I added a spin_lock for setup and transfer_one then setup and
> transfer_one's critical region cann't be called

> simultaneously as I know, because the their lock was same lock.

Think what happens if the two SPI devices have different configurations
- for example, a different SPI mode.  The register state won't be
corrupted but the devices will still end up seeing misconfigured SPI
transfers.